The tools used in gear grinding are exposed to constant wear and therefore must be dressed at regular intervals. The abrasive coating of the tools consists of abrasive grains bound in a binding material, wherein during dressing a removal of abrasive grains and binding material of the tool is effected with the objective of changing the abrasive coating for generating the desired profile of the tool and the required profile accuracy (macrogeometry). The tool can be dressed by a rotating dressing tool accommodated in the dressing tool holder, while it remains clamped in the tool holder.
In the dressing method known from the prior art, a desired profile of the tool is achieved on dressing, in that the relative movements between tool and dressing tool, which are necessary for producing the desired profile, are generated by the superposition of a movement of an axis of movement of the dressing unit with a movement of an axis of movement of the machining head.
It is the object of the present disclosure to provide an improved method for dressing a tool. Furthermore, it is the object of the present disclosure to provide an improved gear grinding machine.
In accordance with the present disclosure, this object is at least partially addressed as described herein.
In one example, the present disclosure shows a method for dressing a tool on a gear grinding machine which includes a workpiece holder and a tool holder, wherein the tool holder is rotatable about a first axis of rotation (B1) and is arranged on a machining head which is pivotable via a swivel axis (A1) and is linearly movable via a first linear axis of movement (V1), wherein a workpiece clamped in the workpiece holder can be machined by a tool clamped in the tool holder. The gear grinding machine furthermore includes a dressing unit with a dressing tool holder, which is rotatable about a second axis of rotation (B2), wherein a dressing tool accommodated in the dressing tool holder is used for dressing the tool clamped in the tool holder.
In accordance with the present disclosure it is provided that during the dressing operation the machining head is pivoted and linearly moved by movements of the swivel axis (A1) and the first linear axis of movement (V1) adjusted to each other in dependence on the tool profile to be produced, wherein the relative movements between dressing tool and tool, which produce the desired profile, are at least partly generated by the superposition of the movements of the swivel axis (A1) and the first linear axis of movement (V1). The method according to the present disclosure can be used for example for producing or restoring a desired profile and/or for modifying a profile.
The inventors of the present disclosure have recognized that for generating the relative movements necessary during dressing, no axes of movement of the dressing unit must be employed. These relative movements rather can be generated via the swivel axis (A1) and the first linear axis of movement (V1) anyway present for machining a workpiece. As a result, the axes of the gear grinding machine anyway present can be used better in the method according to the present disclosure. On the one hand, this provides for a more flexible dressing operation, and on the other hand for using a gear grinding machine of simpler construction.
In accordance with the present disclosure, the desired profile of the tool is produced in that by moving the machining head via the swivel axis (A1) and the first linear axis of movement (V1), the rotating tool is guided past the likewise rotating dressing tool for producing the desired profile, while the dressing tool and tool are in engagement with each other.
Advantageously, the swivel axis (A1) of the machining head is perpendicular to the axis of rotation (B1) of the tool holder.
Furthermore advantageously, in the method according to the present disclosure the swivel axis (A1) and the first linear axis of movement (V1) also are used when machining a workpiece on the gear grinding machine.
When machining a workpiece, the swivel axis (A1) in particular can be used for adjusting the angle between the tool axis and the workpiece axis, for example when producing a helical toothing.
Furthermore, the first linear axis of movement (V1) can be used for shifting the tool, for example to bring another point of the tool in engagement with the workpiece.
In accordance with the present disclosure, the dressing unit is arranged on the gear grinding machine such that the machining head with the tool holder is movable relative to the dressing unit via a first linear axis of movement (V1). The linear axis of movement (V1) hence provides the second degree of freedom necessary for producing a desired two-dimensional profile of the tool beside the swivel axis (A1).
Advantageously, the relative movements between dressing tool and tool, which are necessary for producing the desired profile during the dressing operation, are generated solely via a movement of the machining head. In particular, the dressing unit thus can be arranged on the gear grinding machine without a linear axis of movement, and advantageously in a completely rigid manner.
For producing the desired profile, the swivel axis (A1) and/or the first linear axis of movement (V1) of the machining head in addition can furthermore be utilized in accordance with the present disclosure for moving the tool accommodated in the tool holder towards the dressing tool from a grinding position into a dressing position. In particular, the tool can be pivoted by the swivel axis (A1) from a grinding position into the dressing position.
Advantageously, the tool accommodated in the tool holder is moved towards the dressing tool solely by the movements of the machining head.
In the method according to the present disclosure or in the gear grinding machine used for this purpose, it can furthermore be provided that the workpiece holder is rotatable about a third axis of rotation (C1) and the machining head is arranged on a carriage which is movable parallel to the axis of rotation (C1) of the workpiece holder via a second linear axis of movement (Z1).
Advantageously, it can be provided that the first linear axis of movement (V1) allows a linear movement of the machining head relative to the carriage.
Furthermore advantageously, it can be provided that the swivel axis (A1) allows a swivel movement of the machining head relative to the carriage.
Furthermore, it can be provided that the first linear axis of movement (V1) is arranged between the swivel axis (A1) and the carriage. Furthermore, it can be provided that the first linear axis of movement (V1) is vertical to the second linear axis of movement (Z1).
Alternatively, however, it can also be provided that the swivel axis (A1) is arranged between the first linear axis of movement (V1) and the carriage.
Furthermore, it can be provided that the carriage is arranged on a machine column which is movable vertical to the axis of rotation (C1) of the workpiece holder via a third linear axis of movement (X1).
In accordance with the present disclosure, the dressing unit advantageously can be arranged on the carriage, wherein for dressing purposes the relative movements are generated by the axis of rotation (A1) and the first linear axis of movement (V1) arranged between the carriage and the machining head. Since these two axes of movement are sufficient for generating all movements necessary during dressing, the dressing unit can rigidly be arranged on the carriage at least as regards linear movements.
In accordance with the present disclosure, a second dressing unit furthermore can be provided, which via a fourth linear axis of movement (Z3) can be moved towards the first dressing unit and away from the same, in order to vary the distance between the dressing tools accommodated in the dressing tool holders of the first and second dressing units. In the method according to the present disclosure, it is advantageously provided that the two dressing units are used for dressing the tool on two sides.
The method according to the present disclosure also can be used in such machining heads which include two tool holders for accommodating separate tools. Advantageously, the two tools accommodated in the tool holders are dressed by at least one common dressing unit. In particular, it can be provided that after dressing the first tool, the second tool is moved to the dressing unit by swiveling the machining head about the swivel axis (A1). Advantageously, the two tool holders are arranged on a common axis of rotation (B1). Alternatively or in addition, it can be provided that the two tool holders are driven via a common drive.
In addition to the method for dressing a tool according to the present disclosure, the present disclosure furthermore comprises a method for manufacturing a gear wheel on a gear grinding machine, in which a workpiece clamped in a workpiece holder is machined by a tool clamped in the tool holder. In particular, hard finishing of the workpiece is effected by the tool clamped in the tool holder. In accordance with the present disclosure, the tool is dressed according to the method of the present disclosure as described above, in order to produce the tool profile necessary for generating the desired workpiece geometry. The method of the present disclosure for dressing the tool thus allows a particularly flexible, easy and inexpensive manufacture of gear wheels with a desired gear wheel geometry and surface quality.
The present disclosure furthermore comprises a gear grinding machine with a controller, for example, with memory including instructions, for automatically actuating the axes of movement of the gear grinding machine while machining a workpiece and/or while dressing a tool. In accordance with the present disclosure, the controller includes structure for carrying out the above-described methods for dressing a tool. During the dressing operation, the controller advantageously controls the relative movements necessary for producing a desired profile of the tool by correspondingly pivoting the machining head via the swivel axis (A1) and by a linear movement adjusted thereto of the first linear axis of movement (V1). Advantageously, the controller calculates the swivel movements of the machining head necessary for producing a desired profile. Furthermore advantageously, the controller has an input function for inputting data on the desired profile of the tool, from which the relative movements are calculated. Advantageously, the controller is configured such that the dressing function automatically actuates the axes of the gear grinding machine when carrying out the method and steps described above.
In particular, the gear grinding machine furthermore is constructed such as has been described above with respect to the method. In particular, the gear grinding machine includes a tool holder which is rotatable about a first axis of rotation (B1) and is arranged on a machining head which is pivotable via a swivel axis (A1). Furthermore, the gear grinding machine includes a dressing unit with a dressing tool holder, which is rotatable about a second axis of rotation (B2). Furthermore, the machining head with the tool holder can be movable relative to the dressing unit via a first linear axis of movement (V1). Furthermore, the workpiece holder can be rotatable about a third axis of rotation (C1) and the machining head can be arranged on a carriage which is movable parallel to the axis of rotation (C) of the workpiece holder via a second linear axis of movement (Z1). Furthermore, it can be provided that the carriage is arranged on a machine column which is movable vertical to the axis of rotation (C1) of the workpiece holder via a third linear axis of movement (X1). The further construction of the gear grinding machine also can be designed such as has already been described above.
As in the gear grinding machine according to the present disclosure the relative movements between tool and dressing tool are generated during dressing via the first axis of rotation (A1) of the machining head and a further linear axis of movement of the machining head, the dressing unit itself need not have any axes of movement. In accordance with the present disclosure, the dressing unit therefore can rigidly be arranged on an element anyway present in the gear grinding machine, at least as regards linear movements, for example on the carriage or the machine column on which the carriage is arranged. In a particularly advantageous way, the dressing unit is rigidly arranged on the carriage which carries the machining head of the gear grinding machine, at least as regards linear movements.
Therefore, the present disclosure furthermore comprises a gear grinding machine with a workpiece holder and a tool holder, wherein the workpiece holder is rotatable about a third axis of rotation (C1), wherein the tool holder is rotatable about a first axis of rotation (B1) and is arranged on a machining head which is pivotable via a swivel axis (A1), wherein a workpiece clamped in the workpiece holder can be machined by a tool clamped in the tool holder, and wherein the machining head is arranged on a carriage which is movable parallel to the third axis of rotation (C1) via a second linear axis of movement (Z1). The gear grinding machine furthermore includes a dressing unit with a dressing tool holder which is rotatable about a second axis of rotation (B2), so that a dressing tool accommodated in the dressing tool holder is usable for dressing a tool clamped in the tool holder. In accordance with the present disclosure it is provided that the dressing unit is rigidly arranged on the carriage which carries the machining head of the gear grinding machine, at least as regards linear movements. Such gear grinding machine has a particularly simple construction, wherein dressing the tool clamped in the tool holder nevertheless is possible by the dressing unit according to the method of the present disclosure.
Advantageously, the machining head with the tool holder is movable relative to the carriage via a first linear axis of movement (V1), so that for dressing purposes relative movements with two different degrees of freedom between the tool holder and the dressing tool holder can be generated by means of the swivel axis (A1) and the first linear axis of movement (V1).
Advantageously, the gear grinding machine according to the present disclosure includes a controller for automatically actuating the axes of movement of the gear grinding machine while machining a workpiece and/or while dressing a tool. Advantageously, this controller has a function for carrying out a method according to the present disclosure, as it has already been described above.
Advantageously, the gear grinding machine furthermore is constructed such as has already been described above.
Furthermore, the carriage can be arranged on a machine column which is movable vertical to the axis of rotation (C1) of the workpiece holder via a third linear axis of movement (X1).
Furthermore, a second dressing unit can be provided, which via a fourth linear axis of movement (Z3) can be moved towards the first dressing unit and away from the same, in order to vary the distance between the dressing tools to be accommodated in the dressing tool holders of the first and second dressing units. This can be used in particular for dressing a tool on two sides. The axes of rotation of the two dressing units need not necessarily be aligned in parallel. This is the case, however, in an exemplary embodiment.
Advantageously, the above-described method also is carried out for dressing a tool on the gear grinding machine described above.
Independent of the gear grinding machine described so far and the method described so far, the present disclosure may also comprise a gear grinding machine with a workpiece holder and two tool holders for accommodating separate tools, wherein the tool holders each are rotatable about an axis of rotation and are arranged on a common machining head which is pivotable via a swivel axis (A1), wherein a workpiece clamped in the workpiece holder can be machined by tools clamped in the tool holders. In accordance with the present disclosure, it is provided that the two tool holders are arranged on sides of the machining head facing away from the swivel axis (A1). Other than in known double grinding heads, the two tool holders are not oriented towards the common swivel axis (A1) of the machining head, but each point away from the same. As a result, the tools can be mounted on the tool holders more easily and in addition have a greater distance from the swivel axis (A1). This provides advantages both in terms of machining the workpiece alternately by the two tools and in terms of dressing the tools.
Advantageously, the two tool holders are arranged on opposite sides of the machining head. In particular, it can be provided that the tool holders are arranged on one common axis of rotation (B1) or on parallel axes of rotation. Furthermore, it can be provided that the two tool holders are driven via a common drive.
Furthermore advantageously, the two tools accommodated in the tool holders can be dressed by means of at least one common dressing unit. Advantageously, after dressing the first tool, the second tool can be moved to the dressing unit by swiveling the machining head about the swivel axis (A1).
In the machining head with two tool holders according to the present disclosure, two tools can thus be used with only a small additional effort. In particular, two different tools can be arranged on the grinding head, for example tools with abrasive material with different degrees of fineness. Thus, the first tool for example can be used for roughing, while the second tool is used for finishing. By a corresponding adaptation of the grain size to the respective machining operation, an improvement of performance thus is obtained, since a coarse grain can be used for roughing and a fine grain for finishing.
The last gear grinding machine described can be constructed such as has already been described above in detail with respect to the previously described gear grinding machines. In particular, the machining head with the tool holders can be movable relative to the dressing unit via a first linear axis of movement (V1). Furthermore, the workpiece holder can be rotatable about a third axis of rotation (C1) and the machining head can be arranged on a carriage which is movable parallel to the axis of rotation (C) of the workpiece holder via a second linear axis of movement (Z1). Furthermore, it can be provided that the carriage is arranged on a machine column which is movable vertical to the axis of rotation (C1) of the workpiece holder via a third linear axis of movement (X1).
The gear grinding machine likewise can include a controller as it has already been described above. Furthermore, the above-described method also can be carried out for dressing a tool on the gear grinding machine described above.
In the present disclosure, in particular, grinding wheels and/or grinding worms can be employed as tools. The tools advantageously consist of abrasive grains connected with each other. Dressing the tools is effected by removing grain and binding the grinding tool with the objective of changing the abrasive coating for producing a desired profile and the required profile accuracy. In particular, abrasive grains of corundum, CBN or silicon carbide can be used.
As dressing tools, dressing wheels are advantageously employed. In particular, such dressing wheel can be a diamond wheel or a hard-material-coated metal base body.
The present disclosure will now be explained in detail with reference to drawings and exemplary embodiments.